Differential froth flotation of chalcopyrite-sphalerite ores



s. P. MoYER 2,430,778

SPHALERITE ORES Nov.. ll, 1947.

. DIFFERENTIAL FROTH FLOTATION OF CHALCOPYRITE Filed July 9 \\IV 1|` Om QO` Patented Nov. ll, i947 UNHE@ STATES DIFFERENTIAL FROTH FLOTATION F CHALCOPYRITE-SPHALERTE GRES Samuel Payne Moyer, Greenwich, Conn., assgnor to American Cyanamid Company, New `ilorlx, N. Y., a corporation of Maine Application July 9, 1945, Serial No. 603,982

2 Claims. (Cl. 209-467) This invention relates to a process of separating sphalerite from chalcopyrite in ores containing both minerals by means of a selective or froth flotation process.

The differential separation of copper and zinc from ores which contain both minerals is a common procedure in ore dressing. In general the process used is a two-step froth flotation process' in which the rst step constitutes a copper float, commonly using depressants for zinc minerals, such as cyanides. The tailing from the rougher float is then activated with copper sulfate and the zinc oated in the form of a zinc concentrate. In other words, the standard flotation process operates by reason of the fact that in many ores the copper'minerals oat more readily than the zinc minerals and can be separated from them by a differential otation procedure.

Some copper zinc ores, notably certain ores occurring in Canada and the United States, which contain copper in the form of chalcopyrite and zinc in the form of sphalerite, have not proved to be very amenable to the ordinary differential oat, the selectivity of the two steps being inadequate and there being excessive zinc in the copper concentrate and copper in the zinc concentrate.

According to the present invention I have found that under certain very sharply restricted conditions it is possible to treat ores containing copper largely in the form of chalcopyrite and -zinc in the form of sphalerite by differential ilotation process in which the results are-exactly the reverse of the ordinary procedure. In other words, by the process of the present invention it is possible to float sphalerite and leave behind chalcopyrite. By means of the present `invention it is possible to effectively beneiiciate copper zinc ores which were not readily amenable to the ordinary process.

The first step in the process of the` present invention, i. e. the zinc float which is, of course, the critical step, depends on the use of relatively large amounts of copper sulfate, at least about lbs/ton of ore associated with rigidly restricted ranges of lime. When the effective lime is in the range between a minimum of about 1% lbs./ ton and a maximum of about 3 lbs/ton the sphalerite floats in a zinc concentrate having but y little copper and the tailing can then be treated With additional lime, preferably bringing the amount of lime up to 4 lbs/ton or more, and a high grade copper concentrate can then be iioated. i

The water in which the lime and copper sulfate are added to the ore during conditioning is important. I have found that it is necessary for best results to condition the ore With a lime rst and then to add. the copper sulfate. -If the copper sulfatemis added rst optimum results are not obtained. This may be due to the fact that the copper sulfate might react with lime to use upA a portion of it and decrease the amount available for actual conditioning of the ore particles.

The present invention is not limited to a particular sulfide promoter combination. However, by far the best results are obtained by the use of reagents of the dithiophosphate type, preferably dialkyl dithiophosphate, such as sodium diethyl dithiophosphate. Other sulde promoters may be used but it is difficult to obtain satis-A factory control of the first step under practical operating conditions. Therefore, the dithiophosphates constitute the preferred reagents. In the second step, the copper float, any suitable promoter for chalcopyrite may be used. As the pulp already contains dithiophosphate from the zinc float, it is convenient, although not necessary. to add further amounts of dithiophosphates for the second, or copper iioat.

It is an advantage of the present invention that operating conditions are not critical except that the lime concentration must be rigidly maintained within the limits set and generally good flotation practice may be employed. In

line with common iiotation practice, it is thus desirable although not essential, with all ores, to clean both zinc and copper concentrates. As is common in flotation operations the optimum time `of conditioning with the various reagents will vary from ore to ore. It is an advantage of the present invention that the conditioning time is not critical, and it is only necessary to condition thoroughly for a sufficient time to permit the reagents used in conditioning to act on the mineral particles to producethe surface alteration thereof on which the present process depends.

The invention will be described in greater detail in conjunction with the following examples. In these examples the sulfide copper was chalcopyrite and the sulfide zinc sphalerite.

Example I An ore having approximately the following analysis:

Total copper 3.39% Cu Non-sulfide copper 0.ll% Cu Total zinc Li.9l% Zn Non-sulfide zinc I 0.15% Zn Iron s 4,82% Fe Insoluble 66.10% insel. Specic gravity 3.29 sp. gr.

was ground to approximately 50 %325 mesh. It was then conditioned in a flotation cell with 2 lbs/ton of hydrated lime, followed by thorough conditioning with 5 lbs/ton copper sulfate. The pulp was then subjected to a rougher zinc float using sodium diethyl dithiophosphate as a promoter and pine oil as a frother. The tailing was conditioned for a short time with an additional 2 lbs/ton of hydrated lime, a small amount 4 reagent consumption, as well as the metallurgical results, appearing in the following tables:

It will be apparent that a remarkably good recovery of zinc was obtained with little contamination of the concentrate by copper and a good recovery of copper obtained in a high grade concentrate. Overall losses in the iinal rougher tailingfor the copper float amounted to only l1/$70 of the zinc and 8% of the copper.

Example II A different ore having an analysis approximately as follows:

but containing fair amounts of indium and gallium, together with some molybdenum, were subjected to flotation following a` similar procedure as in Example l, the conditioning, grinding and of sodium disecondary butyl dithiophosphate Per l added during conditioning and a copper concen- 5 giltigrfl cem pH (gg): S0614 lilla Piile m trate oated oif using a small amount of addi- Solids tional pine oil. Each concentrate was cleaned once by reotation. The operations and condi- @gg-if 1g tions, as Well as the metallurgical results, are 7.0101051.; 7 shown in the following tables, the symbols NaAF l0 gomiti@ 2 uFloat 4 being used for diethyl dithiopliosphate and 238 01.7.11 Float 2 for disecondary butyl dithiophosphate, respec- CLCUFIGM- 2 tively.

Assays Per cent distribution Per cent Product Weight Pei-Zent Peiilzlent PerI 1cient Per xent Zu Cu In Ga caiariead. 100.00 0. 00 2.07 0. 004 0. 031 100.00 100.00 100.00 100.00 l, C1. zn Conc 13. s3 44.34 7.30 0.02 0.005 92.0 38.3 04.0 0.8 C1.Z11T0i1 4.83 3.50 13. 02 0.01 0.05 2.0 23.0 11.2 3.0 01.000000.- 3.53 1.10 24.33 0.005 0.01 0.0 32.2 4.2 0.4 C1. Cu T51l 2. 0s 1.55 2.52 0. 004 0.10 0. 5 2. 0 1. 9 2. 0 Bghxraiiing 75. 73 0.30 0.14 0.001 0.10 3.4 3.9 17.8 03.2 calaaginzn Ct 18.00 33.70 8.85 0.017 0.017 95.5 01.0 70.1 3.a Calc. Rgh. Cu Ci; 5.01 1.27 10. 24 0.005 0. 043 1.1 34.2 0.1 3.0

It will be noted that even in the case of such an Reagents' Pounds Der on ore where conditions were chosen to obtain maxfigfl per' pH imum recovery of indium, a high grade sphalerite s. C8 C Na P199 23s concentrate was obtainable, although the separa- 0110s (0H): so. AF on tion between zinc and copper was not sharp as Grind 6 under the most advantageous conditions repre- Condition.; 5 sented in Example 1.

6g The procedure of Example II was followed on 00110100131 2 the ore of Example I with varying amounts of gillff copper sulfate for a fixed amount of lime, and CilCuFioat 2 v arying amounts of lime for a fixed amount of copper sulfate. The results are shown in the drawings, in which: Assays Petrrixlgs Fig. 1 is a series of curves giving zinc recovery Product Percent 40 and copper distribution in the zinc and copper Weigh Per cem Per cent concentrate for various amounts of copper zn ou Z C sulfate; l

Fig. '2 is a similar set of curves for various CaIaHead 100.00 4.92 3.29 100.00 100.00 amounts of lime. Cl Zn conc M4 50'38 383 88' 5 10'1 45 The individual tests are shown as points on the 288 6'37 18'29 37 16'0 curves, and it will be apparent that while the 7.30 1.50 28.03 2.3 00.0 copper sulfate may be used in amounts above L52 308 5.04 1 0 2.3 5 lbs/ton without material falling olf in selec- 'gfgifjj 79.66 0,28 0 33 ,1 5 8.0 tivity and recoveries even when it is doubled, the gitngh ,L52 9 38 M5 92.2 26.1 50 lime shows a very sharply deiined range within Cam 'g'g l 83 24 6] 3 3 65 g which optimum resultsare obtained.

U- Ct The amounts of lime given 1n the specific examples above relate to effective lime, which is free to act on the surfaces of the minerals in the conditioning step. With some ores containing large amounts of soluble salts capable of reacting with lime some of the lime may be neutralized and somewhat larger amounts of lime will be needed in order to obtain the requisite amount in a state free to act on the mineral particles.

I claim:

l. A method of separating sphalerite from chalcopyrite in ores containing the same, which comprises conditioning the ore with an amount of eiective lime from 1.75 to 3 lbs/ton, then conditioning with copper sulfate in amounts at least about 5 lbs/ton to 10 lbs/ton, subjecting the conditioned ore, at flotation pulp density, to froth otation with a dithiophosphate sulfide promoter, whereby a concentrate is produced rich in sphalerte and poor in chalcopyrite and a tailing poor in sphalerite and rich in chaloopyrite, conditioning such tailing with additional lime in amounts such that the total amount of eiective 5 lime in the two conditioning steps is in excess of 3 lbs/ton and subjecting the conditioned tailing topfroth flotation in the presence of a dithiophosphate sulfide promoterv to produce a concentrate rich in chalcopyrite and a tailing poor in chalcopyrite.

2. A method according to claim 1 in which the dithiophosphate promoter is a, dialkyl d ithiophosphate.

SAMUEL PAYNE MOYER.

REFERENCES CITED The following references are of record in the 111e of this patent: 1

5 UNITED STATES PATENTS Number Name Date 1,454,838 Borcherdt May 8, 1923 1,636,974 Wiser July 26, 1927 l0 1,552,936 McArthur Sept. 8, 1925 

